U.S. Pat. No. 4,186,982 describes an electrical connector of the type which is intended to be mounted on a large panel-like member, usually referred to as a mother board, and which has holes extending therethrough that are plated on their surfaces. The connector has terminal posts which have compliant portions that can be forced into the holes so that electrical contact will be established with the plated surfaces of the holes. Connectors of this type avoid the requirement that the terminal posts be soldered to conductors on the mother board and for that reason have been widely adopted in the electronics industry.
When a connector assembly of the type described above is assembled to a mother board, a relatively high insertion force must be brought to bear on each of the terminals to force the compliant portion of the terminal post into the plated hole in the mother board. For a common type of connector, this force required for insertion is in the range of 100-130N (Newton) although the force may go as high as 180N when unfavorable tolerances in the terminals and in the holes are involved. Since the housings are of plastic and ordinarily cannot withstand an extremely high compressive force, it is common practice to assemble connectors of the type under consideration to the mother board by designing the terminals and the terminal-receiving cavities in the housing such that insertion punches can be inserted into the cavities and brought to bear against shoulders on the terminals. The insertion punches push the terminals into the holes and the housing is not stressed during the assembly operation. This method of assembly is inconvenient in that the tooling is expensive and complex in that it requires a "special" dedicated insertion punch for each terminal in the connector housing and different types of tooling are required for different types of connectors.
It has been suggested that the connector assembly be designed such that the insertion forces might be applied directly to the connector housing and transmitted through the housing to the terminals rather than applying the insertion force directly to the terminals by the use of separate insertion punches. In fact, one type of connector is available which does use this principle, the terminals having a single laterally extending ear and the terminal-receiving cavities of the housing having a shoulder surface which bears against the ear so that the insertion forces can be applied directly to the housing. This available connector is being used successfully but it has some comparative disadvantages; for example, it was found necessary to design the connector housing in two parts which must be assembled to each other thereby increasing the manufacturing cost over a comparable one-piece housing connector assembly. Furthermore, the arrangement is such that the insertion forces are applied to the ear along a force line which is spaced from the axis of the terminal; in other words, the terminal is eccentrically loaded during insertion and this is undesirable.
The present invention is directed to the achievement of an improved connector of the type described above and capable of being assembled to the mother board by direct application of the insertion force to the connector housing.
An electrical connector assembly in accordance with the invention is of the type comprising an insulating housing having a mounting face and an opposite face which is oppositely directed with respect to the mounting face, a plurality of terminal receiving cavities extending into the housing from the mounting face and a stamped and formed sheet metal terminal in each of the cavities. Each of the terminals has a post portion which extends outwardly from the mounting face, the connector assembly being intended for mounting on one surface of a panel with the mounting face opposed to the one surface of the panel and with the post portions extending into post-receiving holes in the panel. The posts have interference fits in the post-receiving holes and the connector assembly has force receiving and transmitting portions which receive insertion forces and transmit the insertion forces to the post portions when the connector assembly is assembled to the panel and the post portions are forced into the post-receiving holes in the panel. The connector assembly is characterized in that each of the terminals has a longitudinal terminal axis extending inwardly from the mounting face towards the opposite face. Each terminal further has a yoke portion which is proximate to the mounting face, a shank portion extending along the terminal axis towards the opposite face centrally from the yoke portion, and a pair of ears extending from the yoke portion on a first pair of opposite sides of the shank portion. The ears extend laterally of the terminal axis and have force-transmitting surface portions which face towards the opposite face. Each of the cavities is enlarged adjacent to the mounting face for reception of the yoke portion and the ears. Each cavity has force transmitting cavity wall surface portions which are opposed to, and against, the force transmitting surface portions of the ears to that upon loading the connector assembly adjacent to the one surface of the panel with the post portions of the terminals extending into the post-receiving holes and upon application of insertion forces to the opposite face, the opposite face will function as a force-receiving face and the insertion forces will be transmitted through the housing and through the force transmitting surface portions of the cavities and the ears to the posts and the posts will be driven into the post-receiving holes.
A further embodiment is characterized in that the shank portion has a second pair of opposite sides which extend normally of the first pair of opposite sides, the second pair of opposite sides and the adjoining sides of the yoke portions being the rolled surfaces, the first pair of opposite sides being the sheared edge surfaces. Each of the ears has a fixed end and a free end, the fixed ends being integral with the yoke portion. The ears extend obliquely with respect to the terminal axis from their fixed ends at an angle in the range of about 30.degree. to 60.degree..
A further embodiment is characterized in that the force transmitting surface portion of each of the ears extends from the fixed end of the ear to the free end, the force transmitting cavity wall surface portions associated with each ear extending to a location adjacent to the fixed end of the ear and the force transmitting surface portion of each ear are, in part, beside the shank portion. A further embodiment is characterized in that the free end of each ear has an edge which is between the rolled surface and the sheared surface and the force transmitting surface portions extend past the edge and include the adjacent sheared surface. A further embodiment is characterized in that the housing is a one-piece molding, the terminals having been inserted into the housing from the mounting face, the yoke portions of the terminals having rearwardly facing shoulder surfaces which are co-planar with the mounting face.